>From 220cb3b652abcf6a68b20c4bda4cfd426703d3c1 Mon Sep 17 00:00:00 2001 From: H. Peter Anvin Date: Mon, 30 Jun 2008 23:48:35 -0700 Subject: [PATCH] x86 acpi: on wakeup, ljmp directly after writing CR0.PE Impact: possible resume failures on AMD Elan, others? Intel documents that writing cr0 should be immediately followed by a ljmp, and that "failures are readily seen" if the processor enters SMM at this point. We believe this has been observed on the AMD Elan, so stick strictly to the script and do an ljmp immediately after a change to CR0.PE in all circumstances. Signed-off-by: H. Peter Anvin --- arch/x86/kernel/acpi/realmode/wakeup.S | 13 +++++-------- arch/x86/kernel/acpi/realmode/wakeup.h | 6 ++---- arch/x86/kernel/acpi/sleep.c | 4 +++- 3 files changed, 10 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/acpi/realmode/wakeup.S b/arch/x86/kernel/acpi/realmode/wakeup.S index f2c16d2..7e54e40 100644 --- a/arch/x86/kernel/acpi/realmode/wakeup.S +++ b/arch/x86/kernel/acpi/realmode/wakeup.S @@ -25,10 +25,8 @@ pmode_gdt: .quad 0 realmode_flags: .long 0 real_magic: .long 0 trampoline_segment: .word 0 -_pad1: .byte 0 -wakeup_jmp: .byte 0xea /* ljmpw */ -wakeup_jmp_off: .word 3f -wakeup_jmp_seg: .word 0 +wakeup_seg_ptr: .word 3f-2 /* the segment in the ljmpw */ +_pad: .long 0 wakeup_gdt: .quad 0, 0, 0 signature: .long 0x51ee1111 @@ -49,8 +47,7 @@ _start: movl %cr0, %eax orb $X86_CR0_PE, %al movl %eax, %cr0 - jmp 1f -1: ljmpw $8, $2f + ljmpw $8, $2f 2: movw %cx, %ds movw %cx, %es @@ -60,7 +57,7 @@ _start: andb $~X86_CR0_PE, %al movl %eax, %cr0 - jmp wakeup_jmp + ljmpw $0, $3f 3: /* Set up segments */ movw %cs, %ax @@ -134,7 +131,7 @@ wakeup_idt: .word 0xffff /* limit */ .long 0 /* address */ .word 0 - + .globl HEAP, heap_end HEAP: .long wakeup_heap diff --git a/arch/x86/kernel/acpi/realmode/wakeup.h b/arch/x86/kernel/acpi/realmode/wakeup.h index 69d38d0..0dcdbc7 100644 --- a/arch/x86/kernel/acpi/realmode/wakeup.h +++ b/arch/x86/kernel/acpi/realmode/wakeup.h @@ -24,10 +24,8 @@ struct wakeup_header { u32 realmode_flags; u32 real_magic; u16 trampoline_segment; /* segment with trampoline code, 64-bit only */ - u8 _pad1; - u8 wakeup_jmp; - u16 wakeup_jmp_off; - u16 wakeup_jmp_seg; + u16 wakeup_seg_ptr; + u32 _pad; u64 wakeup_gdt[3]; u32 signature; /* To check we have correct structure */ } __attribute__((__packed__)); diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c index c8c7e7a..08698ca 100644 --- a/arch/x86/kernel/acpi/sleep.c +++ b/arch/x86/kernel/acpi/sleep.c @@ -34,6 +34,7 @@ static char temp_stack[10240]; int acpi_save_state_mem(void) { struct wakeup_header *header; + u16 *wakeup_seg; if (!acpi_realmode) { printk(KERN_ERR "Could not allocate memory during boot, " @@ -43,6 +44,7 @@ int acpi_save_state_mem(void) memcpy((void *)acpi_realmode, &wakeup_code_start, WAKEUP_SIZE); header = (struct wakeup_header *)(acpi_realmode + HEADER_OFFSET); + wakeup_seg = (u16 *)(acpi_realmode + header->wakeup_seg_ptr); if (header->signature != 0x51ee1111) { printk(KERN_ERR "wakeup header does not match\n"); return -EINVAL; @@ -50,7 +52,7 @@ int acpi_save_state_mem(void) header->video_mode = saved_video_mode; - header->wakeup_jmp_seg = acpi_wakeup_address >> 4; + *wakeup_seg = acpi_wakeup_address >> 4; /* GDT[0]: GDT self-pointer */ header->wakeup_gdt[0] = (sizeof header->wakeup_gdt - 1) + -- 1.5.4.1